cartilaginous joint

joint

[joint]

the site of the junction or union of two or more bones of the body; its primary function is to provide motion and flexibility to the frame of the body. Some are immovable, such as the sutures where segments of bone are fused together in the skull. Others, such as those between the vertebrae, are gliding joints and have limited motion. However, most joints allow considerable motion. The most common type are the synovial joints, which have a complex internal structure, composed not only of ends of bones but also of ligaments, cartilage, the articular capsule, the synovial membrane, and sometimes bursae.

acromioclavicular joint the point at which the clavicle joins with the acromion.

ball-and-socket joint a synovial joint in which the rounded or spheroidal surface of one bone (the “ball”) moves within a cup-shaped depression (the “socket”) on another bone, allowing greater freedom of movement than any other type of joint. See illustration. Called also polyaxial or spheroidal joint.

composite joint (compound joint) a type of synovial joint in which more than two bones are involved.

condylar joint (condyloid joint) one in which an ovoid head of one bone moves in an elliptical cavity of another, permitting all movements except axial rotation; this type is found at the wrist, connecting the radius and carpal bones, and at the base of the index finger. See illustration.

gliding joint a synovial joint in which the opposed surfaces are flat or only slightly curved, so that the bones slide against each other in a simple and limited way. The intervertebral joints are this type, and many of the small bones of the wrist and ankle also meet in gliding joints. Called also arthrodial joint and plane joint.

hinge joint a synovial joint that allows movement in only one plane, forward and backward. Examples are the elbow and the interphalangeal joints of the fingers. The jaw is primarily a hinge joint but it can also move somewhat from side to side. The knee and ankle joints are hinge joints that also allow some rotary movement. See illustration. Called also ginglymus.

pivot joint a synovial joint in which one bone pivots within a bony or an osseoligamentous ring, allowing only rotary movement; an example is the joint between the first and second cervical vertebrae (the atlas and axis). See illustration. Called also rotary or trochoid joint.

sacroiliac joint the joint between the sacrum and ilium in the lower back; see also sacroiliac joint.

saddle joint a synovial joint whose movement resembles that of a rider on horseback, who can shift in several directions at will; there is a saddle joint at the base of the thumb, so that the thumb is more flexible and complex than the other fingers but is also more difficult to treat if injured.

synovial joint a specialized joint that permits more or less free movement, the union of the bony elements being surrounded by an articular capsule enclosing a cavity lined by synovial membrane. Called also articulation and diarthrosis. A capillary network in the synovial membrane provides nutrients and synovial fluid to nourish and lubricate the joint space. Strong fibrous bands or cords (ligaments) give strength and security to synovial joints. The majority of the body's joints are of this type. They are divided into five types according to structure and motion: ball and socket, gliding, saddle, hinge, and pivot.

car·ti·lag·i·nous joint

[TA]

a joint in which the apposed bony surfaces are united by cartilage; they are divided into synchondroses and symphyses; in synchondroses, the cartilage connecting the apposed surfaces is, as a rule, ultimately converted to bone, as between epiphyses and diaphyses of long bones; exceptions are the sternal synchondroses and the cartilaginous union of the first rib and the manubrium of the sternum; in symphyses the bones are connected by a flat disc of fibrocartilage that remains unossified throughout life; for example, the intervertebral disc and the symphysis pubis.

joint

the site of the junction or union of two or more bones of the body. See also arthritis. The primary functions of joints are to provide motion and flexibility to the skeletal frame, or to allow growth.

Some joints are immovable, such as certain fixed joints where segments of bone are fused together in the skull. Other joints, such as those between the vertebrae, have extremely limited motion. However, most joints allow considerable motion.

Many joints have a complex internal structure. They are composed not merely of ends of bones but also of ligaments, which are tough whitish fibers binding the bones together; cartilage, which is connective tissue, covering and cushioning the bone ends; the articular capsule, a fibrous tissue that encloses the ends of the bones; and the synovial membrane, which lines the capsule and secretes a lubricating fluid (synovia).

Joints are classified by variations in structure that make different kinds of movement possible. The movable joints are usually subdivided into hinge, pivot, gliding, ball-and-socket, condyloid and saddle joints.

For a complete named list of joints in the body see Table 11.

arthrodial joint

gliding joint.

ball-and-socket joint

a synovial joint in which the rounded or spheroidal surface of one bone ('ball') moves within a cup-shaped depression ('socket') on another bone, allowing greater freedom of movement than any other type of joint. Called also spheroidal joint.

biaxial joint

permits movement around two axes.

cartilaginous joint

one in which the bones are united by cartilage, providing either slight flexible movement or allowing growth; it includes symphyses and synchondroses.

condyloid joint

one in which an ovoid head of one bone moves in an elliptical cavity of another, permitting all movements except axial rotation. Called also condylar joint.

a disease of the joints of all species and all ages but reaching a particularly high prevalence in pen-fed young bulls in which it is characterized by the sudden onset of lameness in a hindlimb, with pain and crepitus in the hip joint and rapid wasting of the muscles of the croup and thigh. There is a family predisposition to this degenerative arthropathy; it is exacerbated by a diet high in phosphorus and low in calcium and dense in energy so that the bull has a high body weight and is growing fast. The onset is acute and often precipitated by fighting or mating. The disease may not develop until 3 or 4 years of age in bulls that are reared at pasture. Called also coxofemoral arthropathy. See also hip dysplasia.

a synovial joint in which the opposed surfaces are flat or only slightly curved, so that the bones slide against each other in a simple and limited way. The synovial intervertebral joints are gliding joints, and many of the small bones of the carpus and tarsus meet in gliding joints. Called also arthrodial joint and plane joint.

hinge joint

a synovial joint that allows movement in only one plane, through the presence of a pair of collateral ligaments that run on either side of the joint. Examples are the elbow and the interphalangeal joints of the digits. The jaw is primarily a hinge joint, but it can also move somewhat from side to side. The carpal and tarsal joints are hinge joints that also allow some rotary movement. Called also ginglymus.

hip joint

the joint between the head of the femur and the acetabulum of the hip bone; loosely called hip.

hyaline cartilage joint

see cartilaginous joint (above).

joint hyperextension

joint can be extended beyond the normal position.

joint hypermobility

usually a congenital defect with all joints affected. Degree varies from extreme, in which limbs can be tied in knots and animal unable to stand, to mild, in which the patient is able to walk but the gait is abnormal. There may be additional defects such as pink teeth lacking enamel and dermatosparaxis (hyperelastosis cutis). See also hereditary collagen dysplasia.

knee joint

1. the joint between the femur and tibia, fibula and patella.

2. in large ungulates the compound joint between the radius, ulna, carpus and metacarpus.

joint mouse

fragments of cartilage or bone that lie free in the joint space. See also joint mouse.

osseous joint

inflexible joint composed of bone; called also synostosis.

pivot joint

a joint in which one bone pivots within a bony or an osseoligamentous ring, allowing only rotary movement; an example is the joint between the first and second cervical vertebrae (the atlas and axis).

plane joint

see gliding joint (above).

joint receptors

sensory nerve endings capable of detecting the position or angle of the joint.

saddle joint

the articulating surfaces are reciprocally saddle-shaped and permit movement of all kinds, though not rotation, e.g. interphalangeal joints in the dog.

spheroidal joint

see ball-and-socket joint (above).

synarthrodial joint

a fixed joint.

synovial joint

a specialized form of articulation permitting more or less free movement, the union of the bony elements being surrounded by an articular capsule enclosing a cavity lined by synovial membrane. Called also diarthrosis and diarthrodial joint.

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